Characteristic of Mild Acid Functionalized Multiwalled Carbon Nanotubes towards High Dispersion with Low Structural Defects

Multiwalled carbon nanotubes (MWCNTs) have a great potential in wide applications but faces limitation in term of dispersion feasibility. The aggregation of MWCNTs floss has restricted its usage and thus, acid treatment is expected to promote the MWCNTs reaggregation. The functionalization process of MWCNTs involves oxidation reaction using mild aqueous acid mixture of HNO3 and H2SO4 (1:3 v/v), via ultrasonication technique. The results were then confirmed by Fourier Transform Infrared Spectroscopy (FTIR), Xray Diffraction (XRD), Thermogravimetry Analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis. From the FTIR spectrum, the existence of carboxyl group indicates the oxidation of MWCNTs on the outer surface wall. TEM and FE-SEM micrographs show the occurrence of surface modification on the MWCNTs structure. The method used in functionalization MWCNTs has created fragmented structure toward the functionalized MWCNTs. TGA analysis on functionalized MWCNTs also shows the presence of the oxygenated group decomposition. Finally, a well dispersed of MWCNTs colloidal was successfully obtained with less MWCNTs structure collapsed.